Skip to main content

Full text of "The manufacture and properties of iron and steel"

See other formats


SEGREGATION AND HOMOGENEITY.
247
arc- given in Table XIII-H, and show that the variations in any one heat are in the third place from the decimal point.
TABLE XIII-H. Variations in Carbon Content Due to Analytical Errors.
ecea showing the highest carbons in the heat, and Group B of those showing the lowest.
BettNo.	Group.	. Composition; percent.					
		Original u giin in TabU IIII-G.			Reworked.		
		Carbon by color.	P.	Mn.	Duplicate determinations by color.		Average of group by combustion.
BOSS	A	.15 .16	.018 .015	.82 .82	.18 .13	.14 .13	.118
	B	.11	.015	.81	.13	.14	.124
8384	A	.10 .17 .17	.025 .022 .024	.48 .47 .45	.18 .17 .15	.10 .18 .16	.165
	B	.11 .12 .12	.024 .024 .020	.40 .48 .46	.17 .15 .16	.17 .16 <"	.168
8280	A	.15 .17	.028 .026	.44 .44	.14 .14	.14 .15	.150
	B	.11 .10	.024 .018	.42 .42	.13 .14	.13 .14	.149
SEC. Xllle.—Acid rivet and angle steel.—A good opportunity of investigating the homogeneity of a heat of steel occurs in the manufacture of rivet rods and angles, where tests may be taken from many different members. In the case of rivet rods, the test-pieces represent the entire cross-section of the ingot, and include the segregated portions. Table XIII-I gives records obtained from several tests taken at random from the rivet rods from five different heats, without any .knowledge as to what part of the heat or what part of the ingot the tests came from. The natural bars are arranged in the order of tensile strength, while in parallel columns are the results obtained by annealing the same bar. Although all the pieces of one heat were annealed at the same time, and with care to have all conditions uniform, the variations in the strength of the treated bar are independent of the variations in the natural bar. This would indicate that the differences are due to irregularities in rolling and to determinative errors rather than to variations in the metal.